Let us consider for a moment the Hollywood performance that never gets nominated for awards but can be just as indelible as any Oscar-winning role. I'm referring to the celebrity interview that goes viral.

Typically interviews that are done during a movie's press tour have an ephemeral quality. But every once in a while you get a performance, as if the actor decided to give the world a bonus sideshow.

Earlier this year while promoting "Oz the Great and Powerful,"Mila Kunischarmed the pants off anyone with a pulse when she playfully went off-message with a blundering BBC radio reporter. The interview has logged 11.5 million views on YouTube. But was it instrumental in helping the movie gross $500 million worldwide? Probably not.

Exhibit C: Rhys Ifans, the British actor best known as Hugh Grant's lanky roommate in "Notting Hill," went scorched-earth on Times of London reporter Janice Turner while promoting a TV drama airing in the U.K.

Each is a performance of epic proportions, and just the latest in a long tradition of combative interviews. It's hard to know exactly why these things go off the rails. Celebrities and journalists are both guilty of unprofessional and less-than-polite behavior. Publicity interviews are strange even under the best circumstances. An artificial but collegial relationship has to spontaneously occur between two people who have often never met. That becomes complicated if one side of the equation is having a bad day. Or if both parties dislike each other on sight. (See: Eisenberg and Univision's Romina Puga.)

If you do this job long enough — be it actor or journalist — you will encounter your share of uncomfortable interviews. The end product can be shocking and notorious and, of course, entertaining for all its schadenfreude.

"Nina, this is so boring, you have to move it along," Ethel Kennedy told me minutes into our conversation last fall about the HBO bio doc "Ethel." That interview was a master class in "Have I done something wrong or does this person really just not want to talk?"

My colleague Luis Gomez had his own run-in this spring with a movie star who came through Chicago in service of the Jackie Robinson baseball film "42": "If getting reamed by the notoriously grumpy Harrison Ford is a rite of passage for entertainment reporters, you could say I was finally initiated into the club."

Interviews in service of a movie are blatantly transactional relationships. At their worst they can leave everyone involved feeling dirty: "Because (actors) hate the game too," Turner writes in her Ifans piece, "and particularly since it is mainly conducted in hotel suites, you feel as if you're engaged in an odd form of prostitution, one where it remains unclear who is the hooker and who the john."

You have to assume most aspects of an actor's celebrity are calculated. Lainey Lui is a reporter for "etalk" (a version of "Access Hollywood" that airs in Canada) and she also runs Laineygossip.com, an addictive website that analyzes the ways in which celebrity images are shaped and manipulated.

"Tommy Lee Jones is notorious for not being the best at an interview," Lui said by way of example. Entertainment Weekly interviewed him for "Lincoln" with a headline that said it all: "Who's Afraid of Tommy Lee Jones? Just about everybody!" "But that fits into the Tommy Lee Jones brand," said Lui. "So is it going to hurt him to be truculent with journalists? No."

But does this performance of marketing the movie itself — and whether or not an actor wants to play ball — even matter in terms of a movie's prospects?

I asked Paul Dergarabedian, who heads the box-office division of Hollywood.com. "I don't think it matters," he said, "not in a negative way. It's the old adage: There's no such thing as bad press. For a contentious interview to go viral is money in the bank for these movies. It's at least getting the name of the movie out there. That's what raises awareness.

"Now, there's a difference between awareness of a movie and wanting to see a movie. You can have huge awareness but have no one show up."

Let's look at "Now You See Me," which has grossed $65 million since opening in theaters last month. The budget was $75 million. Those numbers don't look good. "Actually," Dergarabedian said, "the movie opened much bigger than expected and held really well this past weekend. And I think the Jesse Eisenberg interview may have actually helped the movie because everyone was talking about it." Close to 1 million people have clicked on that interview, which features Eisenberg sitting next to a poster for the movie. He is droll and casually insulting, as if in homage to his performance as Mark Zuckerberg in "The Social Network."

But what if an actor goes way off-brand, like Hill, who became indignant over Rolling Stone reporter Erik Hedegaard's query about flatulence: "I'm not answering that dumb question! I'm not that kind of person! Being in a funny movie doesn't make me have to answer dumb questions. It has nothing to do with who I am."

"The movie trumps all, unless he did something so egregious and so beyond-the-pale," said Dergarabedian. "If you really want to see a movie, none of this behavior will stop you from seeing it."